Image coding apparatus and method

Abstract

Interlace images are separated at every field by a frame/field transforming section, and wavelet transformation is performed for every field by an interfield wavelet transforming section. Specifically, a plurality of odd or even fields in time series are determined as one group, these fields are subjected to the wavelet transformation to separate at predetermined spatial frequencies. Among the plurality of images separated at predetermined spatial frequencies, a motion vector common to the groups is calculated in view of a change with time of an arbitrary image component to perform motion compensation. The images subjected to the interfield wavelet transformation are further subjected to wavelet transformation by an intrafield wavelet transforming section so to be coded. Thus, an operational volume for calculating motion vector for the image coding is reduced, and block distortion is remedied.

What is claimed is:  
     
         1 . An image coding apparatus for compression coding input images and outputting images, comprising: 
 an interimage transforming section, which treats a plurality of input images in time series as groups and separates them into a plurality of images corresponding to predetermined spatial frequency bands; and    a coding section, which performs coding of the plurality of images output from the interimage transforming section.    
     
     
         2 . The image coding apparatus according to  claim 1 , wherein the coding section includes a detecting section which detects a motion vector according to a change with time of images corresponding to the predetermined spatial frequency bands output from the interimage transforming section.  
     
     
         3 . The image coding apparatus according to  claim 2 , wherein the coding section includes an intraimage transforming section which further separates the images whose motion vector has been detected into images corresponding to the predetermined spatial frequency bands.  
     
     
         4 . The image coding apparatus according to  claim 1 , wherein the interimage transforming section treats the plurality of input images as groups not to overlap one another before processing.  
     
     
         5 . The image coding apparatus according to  claim 1 , wherein the interimage transforming section comprises a filter section which separates the plurality of input images into low frequency components and high frequency components and further separates the resulting low and high frequency components into their respective low frequency components and high frequency components.  
     
     
         6 . The image coding apparatus according to  claim 1 , wherein the interimage transforming section comprises a filter section which separates the plurality of input images into low frequency components and high frequency components and further separates the resulting low frequency components into their respective low frequency components and high frequency components.  
     
     
         7 . The image coding apparatus according to  claim 1 , wherein the interimage transforming section includes a filter section which separates the plurality of input images into low frequency components and high frequency components and further separates the resulting high frequency components into their respective low frequency components and high frequency components.  
     
     
         8 . An image coding method for compression coding input images and outputting images, comprising: 
 a step of performing interimage transformation to separate a plurality of input images in time series into a plurality of images corresponding to predetermined spatial frequency bands as a unit of processing; and    a step of coding the plurality of separated images.    
     
     
         9 . The image coding method according to  claim 8 , wherein the coding step comprises: 
 a step of detecting a motion vector according to a difference between at least one image among the plurality of images and a corresponding image in the next unit of processing; and    a step of replacing a pixel value of the image corresponding to the detected motion vector with a fixed value.    
     
     
         10 . The image coding method according to  claim 9 , wherein the coding step has an intraimage-transforming step of separating the replaced image corresponding to predetermined spatial frequency bands.  
     
     
         11 . The image coding method according to  claim 8 , wherein the interimage transforming step determines the unit of processing of input images so not to overlap the plurality of input images one another.  
     
     
         12 . The image coding method according to  claim 8 , wherein the interimage transforming step separates the plurality of input images into low frequency components and high frequency components and further separates the low frequency and high frequency components into low frequency components and high frequency components respectively.  
     
     
         13 . The image coding method according to  claim 8 , wherein the interimage transforming step separates the plurality of input images into low frequency components and high frequency components and further separates the low frequency components into low frequency components and high frequency components.  
     
     
         14 . The image coding method according to  claim 8 , wherein the interimage transforming step separates the plurality of input images into low frequency components and high frequency components and further separates the high frequency components into their respective low frequency components and high frequency components.  
     
     
         15 . The image coding apparatus according to  claim 1 , wherein the interimage transforming section separates by wavelet transformation.  
     
     
         16 . The image coding method according to  claim 8 , wherein the interimage transforming step separates the input images by wavelet transformation.  
     
     
         17 . The image coding apparatus according to  claim 3 , further comprising a quantizing section which quantizes by separately controlling a quantizing parameter of the high frequency images among the plurality of images corresponding to predetermined spatial frequency bands output from the intraimage transforming section.  
     
     
         18 . The image coding apparatus according to  claim 17 , wherein the quantizing section determines the quantizing parameter of the high frequency images rough as compared with the quantizing parameter of the low frequency images.  
     
     
         19 . The image coding method according to  claim 10 , further comprising a quantizing step, which quantizes by separately controlling the quantizing parameters of the high frequency images among the plurality of images corresponding to predetermined spatial frequency bands obtained by the intraimage transforming step.  
     
     
         20 . The image coding method according to  claim 19 , wherein the quantizing step determines the quantizing parameter of the high frequency images rough as compared with the quantizing parameter of the low frequency images.